(1) Field of the Invention
This invention relates to soil sampling equipment.
It is frequently desirable to obtain samples of soils in various areas and at varying depths for analysis. In most operations in which the soil sample is required, speed and convenience in obtaining the sample whereby a large number of samples may be obtained in a short period of time are prime factors.
(2) Description of the Prior Art
In investigations of the distribution, type and physical properties of the soil below ground surface level, it is often desirable to be able to extract continuous, preferably undisturbed, samples of soil. The sampling method of sub-surface exploration provides practically continuous and representative samples of the sub-soil and is probably the best method yet devised for obtaining detailed and reliable information on the chracteristics of the sub-soil. A common and efficient type of sampler is the drive sampler which consists essentially of a tube which is advanced into the soil in the axial direction. There are various types of drive samplers in general use and these may be broadly classified in two groups, namely, open samplers and piston samplers. In the case of open samplers, the tube is always open at the lower end; the soil enters the tube as soon as it is forced into the ground. With piston samplers, on the other hand, the lower end of the tube is temporarily sealed, as by a piston or a plug, so that soil can be prevented from entering the sampler until it has been driven into the soil to the desired sampling depth. At that depth, the piston is released or retracted so that further advance of the sample into the soil forces a sample into the lower end of the tube.
Canadian Pat. No. 623,475 issued July 11, 1961 to P. J. Parsons provided a soil sampling device comprising a tubular drill rod having at least one soil sample-receiving opening in the side wall thereof, a piston assembly in the drill rod and having a pair of spaced connected pistons providing a soil sample-receiving chamber therebetween. It also included an axially extending tie bar connected to the piston assembly. The piston assembly was reciprocally mounted in the drill rod for closure of the opening by a selected one of the pistons.
Canadian Pat. No. 654,906 issued Jan. 1, 1963 to A. G. L. Andersson provided soil sampling equipment of the retracted-piston type which could be operated by means of a single line of extensions, thereby materially reducing the advancing and withdrawal time. Such equipment consisted of the combination of a tubular housing, a sample tube detachably connected at its upper end to the housing and formed at its lower end with a cutting edge, and a piston slidably mounted within the sample tube and adapted to seal off the lower end thereof. A piston rod was connected to the upper end of the piston and extended upwardly through the sample tube and the housing, the piston rod being formed at its upper end with an enlarged head portion adapted with the piston in its fully extended position, to engage the upper edge of the housing, so that downward pressure applied to the upper end of the rod would be transmitted to both the housing and the piston. A plurality of arcuate lugs were on the rod and were spaced apart longitudinally thereof. A plurality of arcuate segments were formed on the inner surface of the housing and were likewise spaced apart longitudinally thereof. The lugs and the segments were adapted to cooperate releasably to lock the rod and the housing in downwardly drivable engagement upon partial retraction of the piston through the sample tube, and in upwardly drivable engagement upon further retraction of the piston to its fully retracted position. A plurality of stop members were provided on the inner surface of the housing intermediate of the arcuate segments, the stop members cooperating with the arcuate lugs to limit the rotational movement of the rod relative to the housing, thereby to facilitate alignment of the lugs and the segments for intercoupling the rod and the housing. Vent means were provided between the piston and the inner surface of the sample tube effective with the piston in its partially retracted position to vent the section of the sample tube below the piston. Finally, means were associated with the piston and were adapted, upon movement of the piston upwardly from its partially retracted position, to seal off the vent means so that during the further retraction of the piston in its fully retracted position, a vacuum would be created above a soil sample which was forced into the sample tube upon downward movement of the housing after the initial partial retraction of the piston.